So first convert 2 3/4 to improper fraction
2 3/4=8/4+3/4=11/4
11/4a=19 1/4
convert 19 1/4 to improper
19 1/4=76/4+1/4=77/4
11/4a=77/4
multiply both sdie sby 4
11a=77
divide by 11
a=7
Answer
A ratio is a comparison of two quantities by division. Ratios describe a part-to-part comparison or a part-to-whole comparison. Ratios are written three ways: as a fraction, with a colon, and with the word “to.” The ratio for quantity a to quantity b is : a to b, a over b, and a:b
Since it's a cuboid, you would multiply the dimensions to get the volume.
10cm x 3cm x 2cm = 10cm x 6cm^2 = 60cm^3